Scientists have discovered two new species of mouse lemur in Madagascar, bringing the total number of these tiny primate species to 20.

The grey mouse-lemur, one of 20 mouse lemur species currently known to science

The mouse lemurs were collected during field surveys in 2003 and 2007, and genetic analysis has now shown them to be distinct species. In a paper recently published in the International Journal of Primatology, the scientists named the new species the Marohita mouse lemur (Microcebus marohita) and the Anosy mouse lemur (Microcebus tanosi).

The Marohita mouse lemur is named after the forest in which it was collected, while the Anosy mouse lemur is named after its distribution in the Anosy region in southeast Madagascar.

Miniscule primates

Mouse lemurs are some of the smallest primates in the world. All are nocturnal and live in Madagascar’s forests, where they feed on a range of insects, fruit, flowers, sap and even small vertebrates, such as frogs and geckos.

Although one of the largest mouse lemurs, the grey mouse-lemur is still one of the world’s smallest primates

The two new species are unusually large for mouse lemurs, with the Marohita mouse lemur reaching lengths of 28 centimetres and weights of about 78 grams. This makes it the largest of the known mouse lemurs. At 27 centimetres and around 50 grams, the Anosy mouse lemur becomes the second largest mouse lemur known to science.

New species discoveries

The rate at which new lemur species have been discovered in Madagascar has dramatically increased in the past decade. The mouse lemurs are one of the most species-rich groups of lemurs, but these tiny primates look so similar that genetic analysis is often the only way to tell them apart.

“I would say that in general, it is highly unusual to describe new species of primates in this age of global travel and consequent access to remote areas of the planet,” said Anne Yoder, director of the Duke Lemur Center and one of the authors of the paper. “That said, the number of described lemur species has more than tripled in the last 10 years. A large number of these new species have been mouse lemurs.”

Goodman’s mouse lemur was only discovered in 2005

Mouse lemurs under threat

Like many of Madagascar’s lemurs, the new mouse lemurs are likely to be under threat from human activities. Since the Marohita mouse lemur was first collected, much of the forest it inhabits has been cleared, and the scientists have classified the species as Endangered. The status of the Anosy mouse lemur is not yet known, but it is likely that it will also be classified as Endangered.

Further field studies have been recommended to assess the distribution and population sizes of the newly described lemurs, so that appropriate conservation measures can be put in place to protect them.

Conserving lemurs

The researchers point out the importance of identifying lemur species if they are to be protected. “Knowing exactly how many species we have is essential for determining which areas to target for conservation,” said Peter Kappeler of the German Primate Center, one of the authors of the paper.

Madame Berthe’s mouse lemur is classified as Endangered on the IUCN Red List

According to Yoder, “I suspect that there are even more mouse lemur species out there to be found… Mouse lemurs are morphologically cryptic, they are tiny, they are nocturnal, and they occur in remote places. It therefore makes a lot of sense that the harder we look, the more species we will find.”

As well as identifying and protecting new lemur species, it will also be important to continue working towards the conservation of all lemurs in Madagascar. Public awareness will be an important part of this.

“I have found that the Malagasy people take great pride in their lemurs, as soon as they understand that Madagascar is unique in having lemurs, and also, that certain lemurs are specific only to a particular area,” said Yoder. “Also, and obviously, the government needs to participate in protecting the forests, and in providing economic alternatives to slash and burn agriculture to the Malagasy people.”